Refrigerating apparatus



June 19, 1956 E. w. ZEARFOSS, JR 2,750,757

REFRIGERATING APPARATUS Filed April 27, 1955 I5 Sheets-Sheet 1 IN V EN TOR.

ELMER W. ZEARFOSS Jr. BY/

ATTORNEY June 19, 1956 E. w. ZEARFOSS, JR 2,750,757

REFRIGERATING APPARATUS Filed April 27, 1955 3 Sheets-Sheet 2 FIG. 2

INVENTOR.

ELMER W. ZEARFOSS Jr.

ATTORNEY June 19, 1956 E. W. ZEARFOSS, JR

REFRIGERATING APPARATUS Filed April 2'7, 1955 3 Sheets-Sheet 3 FIG. 3

FIG. 30

i 0 cu r m X IN V EN TOR.

ELMER W. ZEARFOSS Jr.

yaw

ATTORNEY United States Patent REFRIGERATING APPARATUS Elmer W. Zearfoss, Jr., Philadelphia, Pa.

Application April 27, 1955, Serial No. 504,149 11 Claims. (Cl. 62-4) This invention relates to a refrigerating apparatus of the type which includes two selectively controlled evaporator flow paths which are supplied with refrigerant by a single motor compressor unit.

The general object of the invention is to provide an improved refrigerating apparatus of the type set forth. More specifically, the invention relates to an improved flow control device for the refrigerant supplied to a multi-evaporator circuit.

A further object is to produce a simplified apparatus of this type which is less expensive to manufacture and to service.

A still further object of the invention is to produce an improved means of the type set forth which will operate in an efficient and positive manner and which has no moving parts and is therefore trouble free.

For the purposes of this disclosure, the present invention has been described as applied to a two-compartment or freezer-refrigerator combination. Since the invention resides in a flow control device generally, it is applicable to other multi-circuit systems.

These and other objects are attained by my invention as set forth in the following specification and as shown in the accompanying drawings in which:

Fig. 1 is a diagrammatic representation of one embodiment of my invention.

Fig. 2 is a similar representation of a second embodiment of the invention.

Fig. 2a is a fragmentary view, partly in section and partly in elevation, showing a slight modification of the embodiment of Fig. 2.

Fig. 3 is a similar representation of a third embodiment of the invention.

Fig. 3a is a section on line 3a-3a on Fig. 3.

On the drawings the parts forming the subject matter of the invention are shown enlarged, or out of proportion relative to the conventional parts.

The embodiment of Fig. 1 includes a first evaporator 14), for cooling the freezer compartment and a second evaporator 12, for cooling the food storage compartment, of a conventional refrigerator. The manner in which the evaporators are disposed in their respective compartments and the refrigerating apparatus in connection with which said evaporators are used form no part of the invention and are therefore not shown nor described. It is enough for the purpose of this disclosure to say that evaporator is to be maintained at a lower temperature than evaporator 12. The apparatus shown also includes a conventional accumulator 14 for receiving the spent refrigerant from the outlet end of evaporator 10 and a pipe 16 for conducting the spent refrigerant from the accumulator 14 to a compressor 18. The compressed refrigerant flows from compressor 18 through condenser 20 where the compressed gas is liquefied in the usual way and delivered to a restrictor, or capillary tube 22. In order to insure that no liquid refrigerant reaches the compressor, and in order to improve the efiiciency of the apparatus by further cooling the refrigerant in capillary tube 22, pipe 16 is conventionally brought into heat exchange relation with capillary 22 as at 24. The operation of the compressor is controlled by a normally open switch 26 which closes and energizes the compressor when expansion of bellows 28 is brought about by a measured rise in the temperature of evaporator 10, or its enviromnent, and which opens automatically to de-energize the compressor when bellows 28 contracts as a result of a measured drop in the temperature of evaporator 10, or its environment. Capillary tube 22 delivers the liquid refrigerant and the flash gas generated during the flow of the refrigerant through this tube to compartment 30 of a sump which is divided by partition 32 to form a second compartment 34. Compartments 30 and 34' intercommunicate through a nonrestrictive opening 35 near the top of the sump. A restrictor tube 42 is used for conducting liquid refrigerant from compartment 30 to the inlet 44- of evaporator 10. The intake end 46 of restrictor 42 is. below opening 35 but above the discharge end of capil-- lary tube 22. A restrictor tube 49 is used to conduct liquid refrigerant from compartment 34 to evaporator 12, the outlet end 50 of which leads to the intake end, 44 of evaporator 10. The intake end of restrictor tube 49 is below the intake end 46 of restrictor tube 42. By' this arrangement, evaporators 10 and 12 are series connected with reference to refrigerant flow through restric-- tor 49, but are not series connected with reference to refrigerant flow through restrictor 42. Tubes 22, 42 and. 49 are so proportioned that the restrictive effect of each. of these tubes is considerably less than the restrictive: effect of tube 22. By this arrangement, each of restric tors 42 and 49 is alone capable of carrying away all of" the liquid refrigerant delivered to the sump by capillary tube 22. It is to be noted that tube 42 is sufliciently re-- strictive to produce the pressure drop required to meet: the demand of heat exchange shown at 62 and hereinafter explained. An inverted U-shaped tube 54 extends;

outwardly of the sump with its ends 55 and 56 located adjacent the bottoms of compartments 30 and 34. Tube 54 is considerably less restrictive than tube 22 and is therefore also capable of carrying away all of the refrigerant delivered to the sump by capillary tube 22. Associated with evaporator 12 is a bellows 57 which, when contracted due to a drop in the temperature of evaporator 12, closes normally open switch 58 to energize heater 60, and vice versa. Switch 58 is series connected to switch 26.

The operation is as follows: At the beginning of a cycle, and with the temperature of both evaporators above the desired respective values, bellows 57 opens switch 58 to de-energize heater 60 and bellows 28 closes switch 26 to energize the compressor to start the delivery of the refrigerant to compartment 30 of the sump. Some of the gaseous refrigerant reaching compartment 36 will flow through restrictor tube 42 and some of it will flow through opening 35 into compartment 34. From compartment 34 the gaseous refrigerant will flow through restrictor tube 49 to evaporator 12. As liquid refrigerant accumulates in compartment 30 it first submerges the end 55 of syphon tube 54 (which has some gas in the uppermost part thereof) and then flows through restrictor tube 42 to evaporator 10. As above noted, tube 42 is capable of carrying away all of the liquid refrigerant reaching the sump, and therefore only flash gas will flow into compartment 34 and through restrictor 49. As

liquid refrigerant flows through restrictor tube 42, it expands and cools. Therefore by bringing a portion of tube 42 into heat exchange relation with syphon tube 54'at 62, the refrigerant gas in syphon tube 54 is con- ,densed and the liquid refrigerant thus produced runs down and seals the lower end 56 of the syphon tube. With the other end 55 of tube 54 already sealed, and with the pressure within the tube 54 less than the pressure within the sump, tube 54 is drawn full of liquid and a syphon action is set up whereby all of the liquid refrigerant delivered to compartment 30 will flow through tube 54 to compartment 34 and through restrictor 49 to evaporator 12 and to series connected evaporator 10. Since restrictor tube 49 is also capable of carrying away all of the liquid refrigerant which reaches compartment 34, only the flash gas will flow through restrictor 42. The thermal capacity of this flash gas is low and therefore it will have no practical eifect on heat exchange 62, that is, it cannot break the syphon action in tube 54. Therefore, the flow of liquid refrigerant through restrictor tube 49 continues until the temperature of evaporator 12 reaches the desired low value whereupon bellows 57 closes switch 58 and energizes heater 6d. The heat from heater 6t] evaporates the liquid refrigerant in syphon tube 54 and breaks the syphon action so that liquid refrigerant stops flowing into compartment 3 1- and the fiow of liquid refrigerant through restrictor tube 42 is resumed. The heat from heater 6% is enough to overcome the cooling effect produced at 62 by the flow of the liquid refrigerant through restric tor tube 42. This prevents the re-establishment of the syphon action through tube 54 until the temperature of evaporator 12 has again risen to the predetermined high value necessary to activate bellows 57 to de-energize heater 60 whereupon the syphon action through tube 54 will be restablished in the manner above set forth. When the temperature of evaporator 10 has fallen to the predetermined value, bellows 28 opens switch 26 to deactivate the compressor, and when the temperature of evaporator it) again reaches a value high enough to cause bellows 26 to energize the compressor, a new cycle begins. The flow control disclosed, including the sump, the syphon tube, and the heat exchanges should be insulated from ambient or external heat, so that they may respond exclusively to the factors inherent in the system instead of to extraneously imposed conditions which would defeat the purpose of the control.

The embodiment of Fig. 2 differs from that of Fig. l in that an inverted tube 70 is substituted for sump 31; a non-restrictive tube 71 instead of restrictor tube 42 is brought into heat exchange with syphon tube 54; the outlet of restrictor tube 42 leads, through tube 71, to the inlet of evaporator 12 instead of to the inlet of evaporator 1i and restrictor tube 49 leads to the inlet of both evaporator 10 instead of to the inlet of evaporator 12. The only difference in the flow of refrigerant is that, in this embodiment, evaporators are fed by restrictor 42 instead of by restrictor tube 49 as in Fig 1. in Fig. 2 control 58 is reversed so as to close upon a rise in temperature.

Instead of the syphon tube 54 being cut into the outer inverted U-tube 70, as shown in Fig. 2, the syphon tube may be wholly without tube 79 with the lower ends of the syphon tube connected to the lower end of the outer tube or sump 70 as shown in Fig. 2a.

The embodiment of Fig. 3 differs from the other embodiments as follows: The evaporators are parallel instead of being series connected, with restrictor tube 42 feeding evaporator 10 and restrictor tube 49 feeding evaporator 12, the outlets of both evaporators are connected to a common accumulator 14, and liquid refrigerant can only be supplied to one of the evaporators or to the other, but never to both.

The length and the diameter of each of tubes 42 and 49 may be varied according to the restrictive elfect to be achieved. That being the case, it is possible to dispense with tubes 42 and 49 and to provide measured openings in the walls of compartments 30 and 34 and to connect the inlets of the evaporator circuits directly to said measured openings.

What I claim is:

l. A refrigerating apparatus including a first evaporator and a second evaporator, a motor compressor unit for Withdrawing spent refrigerant from said evaporators and for compressing and liquefying it, a closed sump including a first compartment and a second compartment, there being an opening in the upper portion of said sump establishing communication between said compartments, a first conduit for delivering liquid refrigerant and flash gas from said motor compressor unit to said first compartment, a second conduit leading from said first compartment to said first evaporator for delivering the liquid rerigerant reaching said first compartment to said first evaporator, the intake end of said second conduit being below said opening and above the bottom of said first compartment, a third conduit for delivering the liquid refrigerant reaching said second compartment to said second evaporator, the intake of said third conduit being below the intake of said second conduit, a tube connecting said compartments in flow relationship and having its ends near the bottoms of said compartments respectively, said tube being normally filled with flash gas, means for inducing a syphon action in said tube to draw liquid refrigerant from said first to said second compartment to stop the fiow of liquid refrigerant through said second conduit to said first evaporator and to cause the liquid refrigerant to fiow through said third conduit, to said second evaporator, and means for breaking said syphon action to stop the flow of liquid refrigerant to said second evaporator and to restore the fiow of liquid refrigerant to said first evaporator.

2. The structure defined in claim 1 in which said first means is operative to condense the gas in said tube to induce said syphon action and in which said second means is operative to evaporate liquid refrigerant flowing in said tube to break the syphon action.

3. The structure defined in claim 2 in which said first means is in the nature of a heat exchange between a refrigerated portion of said second conduit and a portion of said tube, and said second means is in the nature of a source of heat, and means for activating said source of heat when the temperature of said second evaporator falls to a predetermined value.

4. The structure recited in claim 1 in which said evaporators are series connected with the outlet of said second evaporator leading to the inlet of said first evaporator.

5. The structure recited in claim 4 and means operable by the rise, or by the fall, of the temperature of said first evaporator to activate or to deactivate said compressor.

6. For use in a refrigerating system of the type which includes a condensing unit for delivering liquid refrigerant and two evaporator circuits to be selectively supplied with refrigerant from said condensing unit, a flow control device comprising a first sump and a second sump having their uppermost ends in communication, and an inverted U tube communicating with the lower portions of said sumps; said first sump having a refrigerant inlet port communicating with said condensing unit and also having an outlet port adapted to supply one of said circuits, said second sump having an outlet port disposed at a level below said first outlet port and adapted to sup ply the other of said circuits; a heat exchange means for inducing liquid fioW through said inverted U tube from said first sump to said second sump and toward the other of said circuits; and a second heat exchange means operable to stop the liquid flow through said inverted U tube and to restore the fiow of liquid to said first circuit.

7. The structure recited in accordance with claim 6 and further characterized in that said outlet ports are of flow restrictive dimensions.

8. The structure recited in accordance with claim 6 which is characterized in that the first mentioned heat exchange means comprises a portion of the first evaporator circuit communicating with said first outlet port in heat exchange relation with said U-tube.

9. The structure recited in accordance with claim 6 and further characterized in that the second said heat ex-. change means comprises an electrical resistance heater.

10. The structure recited in claim 6 and further characterized in that said first and second sumps and said inverted U-tube are formed of tubular sections with said inverted U-tube nested within said surnps and disposed for thermal conductivity there.

11. A refrigerating system including a condensing unit for selectively delivering liquid refrigerant to two evaporator circuits, a first sump, a second sump, the uppermost ends of said sumps being in open communication, said first sump having an inlet for condensed refrigerant and an outflow passage adapted to provide flow to one of said circuits, said second sump having an outflow passage 15 disposed at a level below said first outflow passage and adapted to provide flow to the other of said circuits an inverted U-tube communicat ng with the lower ends of said sumps; a first heat exchange means adapted to cool said U-tube and cause flow of liquid from said first sump through said U-tube toward said second outflow passage; and a second heat exchange means operable to heat said U-tube thereby to terminate liquid flow therethrough and to restore the flow of liquid toward said first outflow 10 passage.

References Cited in the file of this patent UNITED STATES PATENTS 

